Chapter 12 - Electricity Flashcards
Define electric current.
When the electric charge flows through a conductor, there is an electric current in the conductor.
Define switch.
Aka plug key, makes a conducting link between the cell and the bulb.
Define electric circuit.
A continuous and closed path of an electric current.
How is electric current expressed?
Rate of flow of charges.
Which direction does electricity flow?
Electrons were not known when electricity was discovered and electric current was considered to be a flow of positive charges. Conventionally, in an electric circuit, direction of flow of electric current is taken as opposite to the direction of flow of electrons.
What is the SI unit of charge?
Coulomb (C) = 6 x 10^18 electrons.
What is the SI unit of electric current?
I = Q/t
Ampere = C/s
Milliampere = 10^-3 A
Micro Ampere = 10^-6 A
What is electric current measured with?
Ammeter, connected in series.
Define electric potential.
Work done to bring a unit charge ‘q’ from one point to another in an electric field.
What is the SI unit of potential difference?
V = W/Q
Volts.
1V = 1J/1C
What is potential difference measured with?
Voltmeter, connected in parallel.
1 mA = ? A
10^-3
1 µA = ? A
10^-6
State Ohm’s law.
“Electric current flowing though a metallic wire is directly proportional to the potential difference across its ends provided the temperature remains the same.”
V = IR
What is resistance?
It is the property of a conductor to resist the flow of charges through it. SI units is Ohm (Ω).
1 Ω = 1 V / 1 A
